A paper feeding roller is incorporated, for example, in a paper feeding mechanism of an image forming apparatus, such as an electrostatic copying machine, a laser printer, a plain paper facsimile machine, or a multifunction apparatus combining the above, etc.
As examples of paper feeding rollers, paper supplying rollers, conveying rollers, platen rollers, paper ejecting rollers, etc., each of which rotates while contacting a sheet of paper, plastic film, etc., to convey the sheet by friction, can be cited.
Conventionally as the paper feeding roller, a roller made of any of various rubbers, for example, natural rubber (NR), urethane rubber, ethylene propylene diene rubber (EPDM), polynorbornene rubber, silicone rubber, polyethylene chloride rubber, etc., is generally used. EPDM, which is excellent in ozone resistance, weather resistance, etc., is preferable.
The paper feeding roller is formed by molding the rubber, such as EPDM, etc., to a tubular shape and then crosslinking the rubber. A shaft coupled to a driving system arranged to perform paper feeding is inserted through and fixed in a central through hole of the paper feeding roller.
A peroxide crosslinking agent may be used to crosslink EPDM (see Patent Document 1).
Also, for a paper feeding roller constituted of a rubber composition combining EPDM and a peroxide crosslinking agent,                using two or more types of EPDM of different ethylene content as the EPDM to reduce tension set to prevent lowering of drag torque by subsidence of inner diameter of the through hole due to aging while imparting an appropriate hardness to the paper feeding roller without filling with a high amount of a filler and lowering wear resistance, and        further using, in addition to EPDM, isoprene rubber (IR) or styrene butadiene rubber (SBR) in combination as a rubber component to prevent lowering of friction coefficient μ due to accumulation of paper dust through repeated paper feeding, etc., have been examined (see Patent Document 2).        